Well, it wont get destroyed, could break in half or something and create a second moon. It just, wont be able to have life on it like there is now because the surface will be on fire, literally. In a few hundred even thousand years, life will start over again. *Cue "It's the Circle of Life"

The speed at which it hits plays a huge role. A meteor hitting earth at 10,000 mph vs a meteor hitting at 900,000,000 mph leave quite a different looking earths.

But I have to say it wouldn't. It would cause a global black out because of dust flying out and blocking the sun and so forth, but people would survive. A LOT of people would die, but many would survive.